Manufacture of chemical sulfate pulp.



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' particularly to the solution which is used in sans CHARLES Ill. WAI'IEAND JOSE]? E; HEIJIN, 0F WILMINGTON, DELAWARE, ASSIGNUAS Um I ONE-THIRDT0 "WILLIAM H. SHARP, 0F PHILADELPHIA, PENNSYLVANIA.

Ito Drawing.

To all whom it may concern:

Be it known that we, CHARLES N. "Warm and J osnr E. HEDIN, of the cityof Wilming ton,-c0unty of Newcastle, and State of Dela- Ware, haveinvented certain new and useful Improvements in the Manufacture ofChemical Sulfate-Pulp, whereof the following is a specification. Ourinvention relates to improvements in the art of manufacturing chemicalsulfate pulp as used in paper manufacture, and more such processes forthe purpose of cooking or digesting the wood. Sodium sulfid hasheretofore been used'in solution for this purpose, but it has beencustomary to obtain the sodium sulfid by the smelting of sulfate of sodawith a mixture of carbonate of soda and organic matter contained intheblack liquor as the result of a preceding process .of digestion. I

According to our process, we obtain the sulfid of sodium in thedigesting liquor by the direct addition of sulfur toa caustic sodasolution.

In the practice of our process we add to a solution of caustic soda (sayabout seven per cent. or eleven degrees Baum) a suficie'nt amount ofsulfur to produce a suitable quantity of sodium sulfid by reaction withthe caustic soda. 'For ordinary purposes, we find that the addition ofsulfur in the amount of about two per cent. of the total liquor usedproduces goodresults. The sulfur should be added to the caustic sodasolution while boiling, and the process should be continued for aboutthree hours before the liquor is ready for use. f

As the result of the addition of the sulfur a portion of the causticsoda has been converted intosodium sulfid leaving additional causticsoda not adected. The liquor thus formed is added in the usual digesterto the wood and the process of digesting practised asknown to thoseskilled in this art;

In this process'the liquor digests the wood with formation of a wasteblack liquor which is drawnod from the wood pulp which is to be used inpaper manufactured Thereafter the Waste liquor is returned arid from itcarbonate of soda is recovered by the usual process which consists inevaporating the water and burning outthe organic matter which leavescarbonate of soda.

Specification of Letters Patent.

This carbonate of soda is then dissolved and lime MANUFACTURE 01ECHEMICAL SULFATE PULP.

added for the production of caustic soda. Accordmg to our process itis'convenient to Patented men. A, IAI "I. Application filed February 3,19M. Serial Ito. MAMA add the sulfur required alongwith the lime duringthis causticizing process, thereby avoiding the necessity of a separateprocess for the production of the sodium sulfid.

- After having thus added the sulfur during the causticizing processwith the production of sodium sulfid, the liquoris then again usedandthe process repeats itself.

By our process the formation of the digesting' liquor is muchsimplifiedl The use of any smelting process is avoided and theproportion of sodium sulfid in the liquor may be regulated with muchgreater nicety than in previous processes. I

There 1s a corresponding savlng 0f the cost of raw material.

Having thus described our invention, we

claim: 1

. 1. The process of manufacturing liquor to be used in thedigestion ofwood pulp, which consists in taking the spent liquor remain ing from aprevious digestion, evaporating the Water therefrom, burning out theorganic matter contained, dissolving the resulting sodium carbonate andat the same time adding lime, wherebycaustic soda is produced, andsufiicient sulfur; to convert part of the caustic soda into sodiumsulfid, and using the liquor thus produced for a succeeding process of,digesting wood.

2. The process of digesting wood pulp for the manufacture of paper,which consists in adding to a caustic soda solution a quantity of sulfursufficient to convert a portion of the caustic soda into sodium sulfid,and

thereafter adding the liquor thus produced to the wood to be digested,drawing ofi from the digested wood pulp the resulting liquor,evaporating the water therefrom, burning the organic matter, dissolvingthe remaining carbonate of soda and adding thereto lime and sulfurwhereby there is produced a solution containing caustic soda and sodiumsulfid and using the liquor thus produced for a succeeding process ofdigesting wood. In testimony whereof, we have hereunto signed our namesat Philadelphia, Pennsyl- Vania, this thirty-first day of January, 1914.

CHARLES N. WAITJE. JUSEF 1E. I-IEDIN.

